EFFECT OF COMPLETION OF VERNALIZATION ON GENERATIVE DEVELOPMENT OF WINTER RAPE (BRASSICA-NAPUS L VAR OLEIFERA) PLANTS

Germinating seeds and young plants of winter rape var. Gorczanski were vernalized for 56-63 days under conditions of 9-hour day, at the temp erature 2 and 5-degrees-C and in continuous darkness at the temperatur e 2-degrees-C. After vernalization the plants grew under conditions en abling to complete vernalization: in a glass-house at the temperature day/night 15/10-degrees-C and in semi natural conditions of open veget ation hall in the period from June till August. After sub-optimal vern alization further growth of the plants at lowered temperature increase d its effectiveness (completion of vernalization). Depending on-the de gree of the vernalization of the plants the completion of their vernal ization was both obligatory, i.e. conditioning the acquisition of the ability of generative development, and facultative i.e. accelerating t his development. It has been demonstrated that the population of plant s of the examined variety is strongly differentiated not only with res pect of vernalization requirements in the particular plants, but also what regards the effectiveness of vernalization completion. New observ ations have been made indicating that the mechanisms controlling the s uccessive phases of generative development, i.e. phase of forming flow er buds and the flowering phase are not identical which may be interpr eted as indicating that the ''flowering factor'' is polymorphous.